The invention concerns a contra-angle for a dental handpiece provided with means for illuminating the site of treatment.
In order to facilitate the work of dental surgeons, there has already cropped up the idea of incorporating in the working instrument, that is, in the dental handpiece itself, lighting means which are arranged to illuminate the site of treatment.
European Pat. No. 34237, for example, proposes lighting means with optical fibers which pass through the different parts of the handpiece and whose light emitting ends are directed towards the end of the tool.
Other systems have also been envisaged, including particularly small electric bulbs incorporated in the end of the head of the contra-angle and directed towards the site of treatment.
The prior art envisaged up to now does not give full satisfaction and exhibits several disadvantages. In the case of bulbs incorporated in the end of the head of the contra-angle, their major disadvantage is their bulkiness. These bulbs must be placed in a very restricted zone into which cooling fluid supply pipes also open out and, even when using minibulbs, it is difficult to reduce their bulkiness optimally. Moreover, since these bulbs have to be placed as close as possible to the site of working, they may come into contact with the enamel of the teeth and may be subjected to impacts which cause damge to the bulbs. It is furthermore impossible to perfectly seal off the space between these bulbs and their housing from the cooling liquid or dust, while leaving therein a sufficient play to be perfectly accessible for the purpose of replacing the bulbs if necessary. In the case of optical fibers, if they are embedded up to the end of the head, it is difficult to orient their light-emitting ends appropriately towards the site of treatment, because they cannot be bent at a sufficient angle and, if they protrude from the handpiece before the end, they are no longer protected and their front end from which the light emerges may be damaged during treatment, which risks decreasing the light flux considerably.